1. Technical Field of the Invention
The present invention relates to an ink jet type recording head to be suitably used for a printer or a plotter.
2. Related Art
A related ink jet type recording head, for example, an ink jet type recording head using a piezoelectric vibrator as a pressure generating element, comprises a nozzle plate having a plurality of nozzle openings provided in a line, a passage forming substrate in which an ink passage for communicating with the nozzle openings from a common ink chamber to a pressure chamber is formed, and a vibrating plate to be a part of a diaphragm of the pressure chamber, and each member is bonded in a lamination state to constitute a passage unit and the passage unit is bonded to a case. The passage forming substrate is fabricated by etching a silicon wafer, for example, and a nozzle plate formed of stainless is bonded to one of surfaces of the passage forming substrate and the vibrating plate is bonded to the other surface. The vibrating plate is constituted by a composite plate member having a resin film laminated on a support plate formed of stainless.
In the passage unit having such a structure, the passage forming substrate formed of silicon sets limitations to the directivity of the etching and the etching should be carried out to leave a silicon crystal (111) surface. For this reason, the pressure chamber and the common ink chamber which are formed on the passage forming substrate put restrictions on shapes. Consequently, there is a problem in that a desirable shape is obtained with difficulty.
Moreover, there is also a problem in that the passage forming substrate is cut out of the silicon wafer so that it has a size restriction and is not suitable for an increase in the size.
Furthermore, there is a difference between a coefficient of linear expansion of silicon to be used for the passage forming substrate and a coefficient of linear expansion of a stainless plate to be used for the support plate of the vibrating plate and the nozzle plate. Therefore, there is also a problem in that the passage unit is flexed with a change in a temperature.
It is an object of the invention to solve the problems and to provide an ink jet type recording head capable of fabricating a pressure chamber and a common ink chamber to have desirable shapes and maintaining a rigidity required for a passage forming substrate.
In order to achieve the object, the invention has been proposed. A first aspect of the invention is directed to an ink jet type recording head comprising:
a passage unit including a passage forming substrate provided with a serial ink passage communicating with a nozzle opening from a common ink chamber through a pressure chamber; and
a pressure generating element for varying pressure within the pressure chamber,
wherein the passage forming substrate is formed by an integral molding using a resin for partitioning the ink passage and a reinforcement as a core of the passage forming substrate.
Regarding the reinforcement of the present invention, the whole of the reinforcement may be buried in the passage forming substrate, and the part of the reinforcement may be exposed to the surface of the passage forming substrate.
A second aspect of the invention is directed to the ink jet type recording head according to the first aspect, wherein a contact portion with ink in the ink passage is formed of the resin.
A third aspect of the invention is directed to the ink jet type recording head according to the first or second aspect, wherein the ink passage is constituted by the common ink chamber, an ink supply port, the pressure chamber and a nozzle communicating port.
A fourth aspect of the invention is directed to the ink jet type recording head according to any of the first to third aspects, wherein the reinforcement is formed of a material having a greater Young""s modulus than that of the resin.
A fifth aspect of the invention is directed to the ink jet type recording head according to any of the first to fourth aspects, wherein the reinforcement is formed of a material having a higher density than that of the resin.
A sixth aspect of the invention is directed to the ink jet type recording head according to any of the first to fifth aspects, the reinforcement is formed of a material having a coefficient of linear expansion which is equal to or smaller than that of the resin.
A seventh aspect of the invention is directed to the ink jet type recording head according to any of the first to sixth aspects, wherein the reinforcement has a thickness set to be equal to or greater than a half of a thickness of the passage forming substrate.
An eighth aspect of the invention is directed to the ink jet type recording head according to any of the third to seventh aspects, wherein the reinforcement is a plate-shaped member having a rectangular opening for surrounding a line of the nozzle communicating ports.
A ninth aspect of the invention is directed to the ink jet type recording head according to the seventh aspect, wherein the thickness of the reinforcement is set to be equal to that of the passage forming substrate, an internal wall portion of the reinforcement is covered with the resin, thereby divining the ink passage.
A tenth aspect of the invention is directed to the ink jet type recording head according to any of the first to eighth aspects, wherein the passage forming substrate is formed by outsert molding to expose one surface of the reinforcement to one surface of the passage forming substrate.
The xe2x80x9coutsert moldxe2x80x9d implies that integral molding is carried out with a part of a core material exposed to the surface of a molded product.
An eleventh aspect of the invention is directed to the ink jet type recording head according to any of the first to ninth aspects, wherein a neutral line of the single reinforcement for bending in a direction of a thickness is made equal to that of the passage forming substrate.
A twelfth aspect of the invention is directed to the ink jet type recording head according to any of the first to eleventh aspects, wherein the passage unit includes a nozzle plate having the nozzle opening formed thereon, and
a coefficient of linear expansion of the passage forming substrate is set to be equal to that of the nozzle plate.
A thirteenth aspect of the invention is directed to the ink jet type recording head according to any of the first to eleventh aspects, wherein the passage unit includes a nozzle plate having the nozzle opening formed thereon, and
a side wall of the ink passage is provided with a draft taper to be enlarged and opened from a junction surface with the nozzle plate in the passage forming substrate toward an opposite surface of the junction surface.
A fourteenth aspect of the invention is directed to the ink jet type recording head according to the twelfth or thirteenth aspect, wherein the reinforcing plate and the nozzle plate are formed of the same metal material.
A fifteenth aspect of the invention is directed to the ink jet type recording head according to any of the first to eleventh aspects, wherein the nozzle opening is formed integrally with the passage forming substrate by the molding using the resin.
A sixteenth aspect of the invention is directed to the ink jet type recording head according to the fifteenth aspect, wherein a bottom portion of the common ink chamber at the nozzle opening side is formed integrally with the passage forming substrate by the molding and the resin in the bottom portion is formed thinly to be a compliance portion.
A seventeenth aspect of the invention is directed to the ink jet type recording head according to any of the first to fourteenth aspects, wherein the passage unit includes a vibrating plate for sealing a part of the pressure chamber and changing the volume of the pressure chamber by deformation, and
the coefficient of linear expansion of the passage forming substrate is set to be equal to that of the vibrating plate.
An eighteenth aspect of the invention is directed to the ink jet type recording head according to the seventeenth aspect, wherein the vibrating plate is constituted by a composite plate member having an elastic film laminated on a support plate, and
the reinforcing plate and the support plate are formed on the same metal material.
A nineteenth aspect of the invention is directed to the ink jet type recording head according to any of the first to eleventh aspects, wherein the reinforcing plate is constituted by a heat generating member for generating heat by supply of a voltage.
A twentieth aspect of the invention is directed to the ink jet type recording head according to the nineteenth aspect, wherein the heat generating member is a ceramics heater.
A twenty-first aspect of the invention is directed to the ink jet type recording head according to any of the first to twentieth aspects, wherein the pressure generating element is constituted by a piezoelectric vibrator.
Further in order to achieve the object, the invention has been proposed. A twenty second aspect of the invention is directed to a method of manufacturing an ink jet type recording head which includes a passage unit having a passage forming substrate provided with a ink passage, the method comprises the step of:
molding the passage forming substrate in a resin for partitioning the ink passage and a reinforcement as a core of the passage forming substrate with using a mold.
A twenty third aspect of the invention is directed to the method of manufacturing the ink jet type recording head according to the twenty second aspect, the molding step includes the steps of:
applying the resin and the reinforcement to a first mold of the mold having a cavity formed in conformity with an external shape of the passage forming substrate;
setting a plate-shaped second mold of the mold on the first mold.
A twenty fourth aspect of the invention is directed to the method of manufacturing the ink jet type recording head according to the twenty third aspect, an abutment surface of the first mold and the second mold is aligned with a junction surface with a nozzle plate in the passage forming substrate.
A twenty fifth aspect of the invention is directed to the method of manufacturing the ink jet type recording head according to the twenty fourth aspect, the reinforcement is buried in the resin.
A twenty third sixth of the invention is directed to the method of manufacturing the ink jet type recording head according to the twenty fourth aspect, a part of the reinforcement is exposed to the junction surface.
A twenty seventh aspect of the invention is directed to the method of manufacturing the ink jet type recording head according to the twenty third aspect, the cavity is inclined to be expanded and opened toward the second mold.
A twenty eighth aspect of the invention is directed to the method of manufacturing the ink jet type recording head according to the twenty third aspect, the cavity has a portion formed in conformity with an external shape of a nozzle opening to integrally forming the nozzle opening with the passage form substrate.
A twenty ninth aspect of the invention is directed to the method of manufacturing the ink jet type recording head according to the twenty eighth aspect, in the setting step, a clearance is provided between the first mold and the second mold to cover a portion to be the nozzle opening with a resin layer,
the molding step further includes the step of wrapping the resin layer to expose the nozzle opening.
The present disclosure relates to the subject matter contained in Japanese patent application Nos. 2000-175120 (filed on Jun. 12, 2001), 2001-173432 (filed on Jun. 6, 2001) and 2000-175656 (filed on Jun. 11, 2001), which are expressly incorporated herein by reference in their entireties.